The present invention relates generally to rotating impellers and more particularly to an impeller designed to rotate near the surface of a liquid to aerate the liquid.
In recent years aerating impellers have been used quite extensively on the surface of liquid sewage for aerating the sewage. Typical of such aeration impellers are those shown in U.S. Pat. Nos. 3,479,017 to Thikotter; 3,576,316 and 3,610,590 to Kaelin; and 3,741,682 to Robertson. Although such devices have functioned in a generally satisfactory manner, problems have been experienced with excessive splashing and misting, insufficient pumping and circulation, and clogging of the impellers during operation. Additionally, these prior art impellers have been of a fixed diameter, and thus if a larger or smaller impeller were needed, an entire unit would have to be substituted in the field.